1.5 vs. 1.6 Roller Rockers

All of this is accurate. The 1.6 will add more lift and some duration to the valves. They also add more force between the lobe and lifter which is multiplied by the spring rate. I never had a problem with longer rockers on stock cams besides pushrod hole size, but on max effort motors... It's a good way to crush the lobes to dust. I do agree with them being a bandaid for wrong cam choice and I really don't like the extra effort in measuring pushrods involved in them. I wouldn't recommend a longer rocker unless the motor was already well broken in and you wanted to see what a little extra valve opening would do.

Ya. Get the correct cam in the first place. If you want to try the 1.6s later, go for it. I wouldn't, though. Waste of $$, waste of time and screws up your valve train geometry. If you buy your cam from the pros (Lunati, Competition. etc.) and actually give them all of your specs, they aren't going to leave any grunt on the table that you could extract by using 1.6 rockers. They will build you a cam that will get all the grunt you are ever gonna get out of your combo!

With your lower lift stock grind and decent heads I suspect you'll see a difference in performance. I'm running a Performer Plus cam with flat tappets. Looking to get more lift with this somewhat aggressive profile I put on a set of Pro Magnum 1.6 rockers, did feel some difference with this. No problems for a couple years now. Really a good mid rpm range cam there. Simple math, lift divided by 1.5 times 1.6 to get result.

Edit: I just noted you said stock duration on that cam, lift? If that cam (roller cam) has some serious lift with the lower duration you may not actually see any real improvement.

If you look at some of the engines built in the engine masters challenge you will see some very high ratio rocker arms. These engines are not built by bench racers but master engine builders that take every factor into account when designing the engines.

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Good point, but most of the stuff that goes into an EMC entry is at the "edge" and you do crazy things to bring up the TQ/HP averages, but I have seen when the engine is sold to a customer, things get changed out, like cam/lifters/PR and rockers.

I have also seen 1.5 RR with bad geometry, and the replacement 1.6 rocker from a different manufacturer was better in every way!!

LowendAdministrator. .a car, a man, a maraca.Staff MemberLifetime Gold Member

I'm opinions on high ratio rocker arms are pretty well known.
Here are the cliff notes:
Camshaft lobe design is a complicated undertaking. Mechanical engineers spend many-many hours working out portions of the design that no-one ever considers; things like lifter contact angle, lifter loft, valve closing speed. These specs are designed with a specific rocker ratio in mind. In most cases, the factory rocker ratio for a given engine (1.52 on a small block).
You (and I) are not more knowledgeable than the engineers who are designing cam lobes. You will not out-smart them with a set of 1.6 ratio rocker arms.
Unless a cam is designed specifically with a higher rocker ratio in mind, leave it alone.

I've been around cars and Chevy's in particular since the 70's. To the best of my memory the stock ratio for small blocks has always been 1.52. I'm sure if you look in some older HP books you will find it there. Most after market companies round the ratio to 1.5.